A viscoplastic model for extrusion is discussed which simultaneously predicts the deformation field, optimal die geometry, and plastic boundaries. The die geometry and plastic boundaries are expressed in terms of chosen trial functions that satisfy certain geometrical and physical constraints. The variational power integral is minimized in the trial plastic domain using FEM technique to determine the deformation field and shape coefficients for the die contour and plastic boundaries. The proposed method is implemented for the optimal design of an axisymmetric streamlined die. The predicted values are in reasonable agreement with the experimental observations and are in conformity with the results published earlier.

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